Value of ambulatory arterial stiffness index and 24-h pulse pressure to predict progression of albuminuria in elderly people with diabetes mellitus

BACKGROUND: Ambulatory 24-h pulse pressure predicts progression of albuminuria in people with diabetes mellitus. It is not known whether the ambulatory arterial stiffness index (AASI) may add to that prediction. METHODS: We compared the multivariate-adjusted association of AASI and 24-h pulse pressure with progression of urine albumin excretion during follow-up in a multiethnic cohort of older people with type-2 diabetes mellitus. The baseline evaluation included office and 24-h ambulatory blood pressure (BP) measurements, and a spot urine measurement of albumin-to-creatinine ratio (ACR). The ACR measurements were repeated annually during 3 years. RESULTS: The AASI was >or=0.55 units in 47% of those exhibiting progression of albuminuria, and in 37% of those without progression (P = .004), whereas 24-h pulse pressure was >or=65 mm Hg in 50% and 38% of those with and without progression, respectively (P = .001). In repeated measures mixed linear model (n = 1043), after adjustment for several covariates including office pulse pressure, AASI in the fourth quartile was independently associated with higher follow-up ACR (P = .024). However, that association did not persist after adjusting for 24-h pulse pressure, which was an independent predictor (P < .001). Cox proportional hazards models examined progression of albuminuria in 957 participants without macroalbuminuria at baseline. The hazard ratio (95% CI) for AASI >or=0.55 units was 1.37 (1.02-1.83) after multivariable adjustment, including office pulse pressure. But AASI was not an independent predictor after adjustment for ambulatory pulse pressure, which was again an independent predictor (P = .033). CONCLUSIONS: Ambulatory 24-h pulse pressure outperformed AASI in predicting progression of albuminuria in elderly people with type 2 diabetes.